It is well-known that the L2 learning process is heavily affected by a well-established habitual perception of phonemes and articulatory motions in the learners' primary language (L1) [1]}, which often cause mistakes and imprecise articulation in speech productions by the L2 learners, e.g., a negative language transfer [1]}, [3]}.
As a feasible tool, computer assisted pronunciation training (CAPT) is often employed to automatically assess L2 learners’ pronunciation quality at different levels, e.g., phone-level [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, word-level [14]}, [15]}, [16]}, [17]}, [18]} and sentence-level [19]}, [20]}, [21]}, [22]}, [23]}.
